Coiled tubing operations may be employed at an oilfield to deliver a downhole tool to an operation site for a variety of well intervention applications such as well stimulation, the creating of perforations, or the clean-out of debris from within the well. Coiled tubing operations are particularly adept at providing access to highly deviated or tortuous wells where gravity alone fails to provide access to all regions of the wells. During a coiled tubing operation, a spool of pipe (i.e., a coiled tubing) with a downhole tool at the end thereof is slowly straightened and forcibly pushed into the well. For example, a clean out tool may be delivered to a clean out site within the well in this manner to clean out sand or other undesirable debris thereat.
Unfortunately, the coiled tubing is susceptible to helical buckling as it is pushed deeper and deeper into the well. That is, depending on the degree of tortuousness and the well depth traversed, the coiled tubing will eventually buckle against the well wall and begin to take on the character of a helical spring. In such circumstances, continued downhole pushing on the coiled tubing simply lodges it more firmly into the well wall ensuring its immobilization and potentially damaging the coiled tubing itself. This has become a more significant matter over the years as the number of tortuous or deviated extended reach wells have become more prevalent. Thus, in order to extend the reach of the coiled tubing, a tractor may be incorporated into a downhole portion thereof for pulling the coiled tubing deeper into the well.
Tractoring and advancement of the coiled tubing through the well is directed by an operator from the surface of the oilfield. Generally this takes place without information provided to the surface as to the status of the operation at the site of the tractor downhole. That is, the real-time acquisition and transfer of data between the area of the tractor and the surface is generally lacking due to challenges involved in acquiring and transferring the data. For example, mud pulse telemetry or the use of wireline cables between a diagnostic tool at the tractor and the surface may be employed to provide well condition information to an operator. However, in the case of mud pulse telemetry, a temporary obstruction in the well is required in order to transmit a fluid pulse uphole. Additionally, data collection may be limited and the system quite complex. Therefore, mud pulse telemetry is generally not employed. On the other hand, the placement of wireline cables all the way through the coiled tubing and to a diagnostic tool at the tractor location presents several challenges as well. For example, wireline cables are difficult to run through the coiled tubing, take up considerable amount of space within the inner diameter of the coiled tubing, may significantly increase the total weight of the coiled tubing equipment, and present challenges related to tension and control compatibility between the separate wireline and coiled tubing lines themselves.